Prothonotary Warbler

Friday, 26 February 2016

Quest for the nest.....

Bald Eagles aren't the novelty they used to be, but they still are a highlight to see.

At one point in the first half of the last century, eagle advocates determined that there was on average an active Bald Eagle nest for every mile of Lake Erie shoreline between Long Point and Point Pelee. But by the early 1970s, there was only one. That was at Rondeau Provincial Park, where historically there had been two active nests. When the first Ontario Endangered Species Act came into effect in 1973, the Bald Eagle was listed along with 11 other species.

The culprit for the decline? Primarily it was the liberal use of DDT, which caused egg shells to become so thin that they broke when the adults attempted to incubate them. There were also deformities in beaks appearing in birds that had hatched, resulting in young birds not being able to fledge.

Even the nesting pair at Rondeau, at least for a few years, did not produce any young, or at least not every year. When young were raised, it was often only a single eaglet.

Of course in many respects, it has been a good news story since that time. DDT was banned, at least in Canada and the US. DDT was still used in developing countries of Latin America and elsewhere, but since eagles didn't migrate to those locales, and the fish they were feeding on here weren't affected by DDT, the plight of the eagle improved considerably.

Adult eagle with fish in its talons

There have been other issues that eagles have faced, including loss of habitat as well as persecution in areas where they weren't protected by legislation due to the perception that they were killing young livestock. In recent years there have been effects by power lines, wind turbines and such. As unfortunate as those incidents are, the Bald Eagle population has continued to climb in numbers.

For example in the early years of the Blenheim/Rondeau Christmas Bird Count (which began in 1939), it was common to get anywhere from 1-11 Bald Eagles on the count. By the late 1950s through the mid 1980s, it was rare to get more than 2-3, and some years none were counted. Since 2000, it has been unusual to get fewer than 10 eagles, with a high of 17 recorded one year.

On the St. Clair NWA Christmas Bird Count (CBC), which started in 1981, Bald Eagles were only counted about half the time for the first few years and only one or two if any. Since 2002, that count has averaged 10 eagles, with more than 20 counted on two of those years. The all-time high of 27 was on the most recent count.

The Wallaceburg/Walpole CBC, which began in 1986, did not have a single Bald Eagle for the first 10 years but in the last decade has only missed them once. The most recent count recorded 8 birds, an all time high for that count.

A new CBC has been started in the Skunk's Misery area, which includes parts of Chatham-Kent, Elgin, Middlesex and Lambton. In only its second year, in early January, 2016, there were 27 Bald Eagles tallied.

Of course some of the count results have been weather related, but in general, this last decade and a half has seen a continual increase in Bald Eagle numbers throughout southwestern Ontario. And it was about a decade ago when the species was re-evaluated and taken off the provincial Endangered Species list. It is currently ranked as Special Concern, a much lower level of significance.

When I was working at Rondeau in the 1970s and 1980s, it was always a highlight to go out to the nest and band the young birds. The adults liked their privacy as well as having good access to the extensive marsh, so getting to their nest was not easy. The next few shots have all been scanned from old slides.

Approaching the nest tree, where the nest is in the upper left hand corner

We had to cross several sloughs, and even with chest waders, it was not always easy to get to the nest without getting wet. Fighting our way through the gnarly buttonbush while carrying equipment made it an additional challenge. During the first few years, a researcher associated with the University of Wisconsin was the lead bander, as he had been keeping tab on all the eagle nests around the lower Great Lakes. Of course there were very few nests to keep track of in those days. On occasion someone from a TV station would join us, to document this newsworthy event. Even though they were told they would need chest waders, they didn't always come prepared. But at least they kept the camera equipment dry.

Once we got to the nest tree, one person would climb the tree, using climbing spurs and ropes (although one time an energetic young fellow just had climbing spurs, and no other equipment. He did it free hand.......That wouldn't happen in today's world, with emphasis on health and safety.....)

The climber would get into the nest, and if we calculated the bird's age closely enough, the birds would stay put. Then each one would be carefully put into a burlap bag and lowered to the ground, where the awaiting crew would take measurements and a blood sample, and then an aluminum band was placed on the leg. Ideally we would band the bird when it was about 5-6 weeks of age. A younger bird might have smaller legs, and the band would be too big for the leg. If the bird was older, it might attempt to jump out of the nest, fledging prematurely.

On one occasion we got a 'jumper' and the eaglet, with wings outspread, floated down to the adjacent marsh. I managed to catch up to it, grasping its lower legs to keep the talons from doing any damage, and took it to the rest of the crew where the banding process was completed. It was returned to the nest in the bag, and it did not attempt to jump again.

Measuring the femur

Putting on the band

Measuring the beak

On occasion, there were even three birds in the nest, certainly an indication of improved health in the adults. Two is the norm, so three birds were a major highlight.

But the main reason for this post is not to present this bit of history....most readers will likely know a good part of it. No, this post is to try and generate interest in finding active nests in 2016, especially in the Chatham-Kent area.

The local Bald Eagles have been in their early stages of courtship and nesting behaviour for a little while now. In fact some may have been busy repairing old nests or beginning new ones, even late last autumn. But now that spring is not all that far off (we hope!) serious nesting activity is near. Egg dates for this latitude around the lower Great Lakes, typically starts in mid-March. The farther south one goes, the earlier the nesting season starts, not surprisingly. For example in Florida, the egg-laying season usually starts in mid-November.

Nests are most visible right now, and until the trees leaf out in May. Active nests will have one or more adults nearby, confirming their active state.

I am aware of up to 18 nests in Chatham-Kent or immediate vicinity.

two at Rondeau, one visible from the Marsh Trail and the second only visible from a small section along the south beach.

Rondeau nest

one in the immediate vicinity of Clear Creek Forest Provincial Park

another one along the Lake Erie shoreline east of Morpeth

one along the Thames River, east of Thamesville. It occurs along an oxbow on the north side of the river, and is visible from Hwy 2/Longwoods Road.

Along oxbow, east of Thamesville

one along the Thames River on the south side and closer to the Delaware of the Thames First Nation

one at the north end of the Scane Sideroad, on the south side of the Thames River

one that used to be adjacent to a small gravel pit northeast of Thamesville, although it may not still be usable, and that pair might now occupy one of the other nest territories not far away

one on the south side of the Thames River, in a tree line south of the Maple City Golf Club

one along the Snye Channel (a.k.a. Chenal Ecarte)

one, or possibly two, along the Lake St. Clair shoreline south of SCNWA

one on the south side of Lighthouse Cove. Technically it is in Essex Co, but it is associated with the Thames River and the river mouth

Lighthouse Cove nest

one in a woodlot east-northeast of Wheatley, although I haven't seen that nest for a few years and it may not still be active

one in a small woodlot north of Talbot Trail, just west of Dillon Road

one in a larger woodlot complex north of Dealtown. It is possible this pair and the one along Dillon Road may be the same, as eagles sometimes have nests that they rotate to.

one along the Sydenham River, east of Dawn Mills.

There is a possible nest in a small woodlot north of Shrewsbury. It is a recently constructed nest, although it is not very large.....yet. To add to the uncertainty, in the last few weeks some of us have seen and photographed Bald Eagles perched on the nest or in nearby trees, and we have also seen and photographed Red-tailed Hawks doing the same thing! It will be interesting to see who eventually makes use of this one. Or since Great Horned Owls typically begin nesting before either eagles or hawks, maybe this one will be used by a Great Horned Owl! Stay tuned....

These are the ones that I am aware of. Not all are necessarily active this year, and likely there are others. Given that Bald Eagles feed on fish a lot, or other creatures of wetlands, nests are typically found within one to two kilometres of a large water body or river.

If you are cruising the countryside in the vicinity of Lake Erie, Lake St. Clair, the Thames River or the Sydenham River, keep an eye open for Bald Eagles or a large cluster of sticks that could be their nest. And if you find something that fits, please let me know, either through a comment on this blog, or via email: prairietramper@gmail.com